In power for decades, he has been sharply criticized for rights abuses and turning the nation from a breadbasket into a financial basket case. The presence of a man widely regarded as a brutal dictator, juxtaposed with a pope who preaches peace, has raised eyebrows.

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Vincent Nichols, the Roman Catholic archbishop of Westminster, who attended the 2011 ceremony, said, according to the Daily Mail, that Mugabe's record on human rights was deplorable and "it felt uncomfortable to be in his presence."

Controversy erupted in 2005, when Britain's Prince Charles found himself seated near Mugabe at the funeral and at one point shook his hand. A spokesman for the prince later said that was a mistake, that Charles was caught by surprise after Mugabe offered his hand.

The Rev. Federico Lombardi, a Vatican spokesman, said last week that the Holy See did not formally invite diplomatic missions to attend the Mass, instead simply informing countries through diplomatic channels that the event is taking place.

Even countries with which the Vatican does not have diplomatic relations, such as Saudi Arabia, are informed of major events such as the installation or funeral of a pope, he said.

The Vatican Press Office said it could not yet provide a full list of attendees for the ceremony. The Bernini Bristol Hotel in Rome confirms it has hotel reservations for a Zimbabwean delegation but did not provide names.

The raid came a day after a national referendum to approve a new constitution that would impose presidential term limits for the first time in Zimbabwe.

The results of the vote are not yet known, and it came just a few months before Prime Minister Morgan Tsvangirai is expected to run against Mugabe in presidential elections. The two leaders entered a power-sharing agreement in 2009

If approved, which is highly likely, the new constitution will give more powers to the parliament and limit the president's. It also introduces a two-term limit of five years each for a president. But the limit would not apply retroactively, which means Mugabe could have 10 more years as head of state if he is re-elected.